What would more MP mean to you ?

Given the performance of the Sony sensors found in the D800 and A7R, I would say more MP would mean the existence of a newer sensor design (i.e., the updated sensor will have other qualities than just more MP), and we could leave the arguments that Fuji makes more bodies based on old sensors, milking things.

Landscape guys would appreciate more MP.

But, most importantly, if the MP increase is big enough like it was for the D800, your lens better be top notch to support the higher resolution. Otherwise, time to buy more glass.